No, you cannot. However, I have developer a Viewer control which views any file type that the OS can view. This was mostly done by using a webbrowser control and hooking into different events. Now, it IS possible to handle specific events and get the type of object that is being loaded into the browser. Using this, you could write another layer to your code that can handle the multiple versions of MS Office which could stop a user from modifying a Document. For PDFs it doesn't really matter, only about 5% - 10% of employees actually have a full version of Acrobat where they could actually manipulate a PDF. I cannot go into futher details because my code belongs to my company and I cannot distribute it. But the webbrowser will be your best bet. In .NET 2005, the webbrowser has been fully overhauled to be .NET friendly.